Lost-motion-compensating means for gear-hobbing machines



E. BUCKINGHAM LOST MOTION COMPENSATING MEANS FOR GEAR HOBBING MACHINES Filed 00?,- 12, 1922 V 12: IV s INVENTGR ATTORNEY Patented Jan. 19, 1926.

UNITED STATES PATENT orrica.

nsane nocxrivcnam, or na'a'rronn, connnorropa Assrcnon ITO rnAar & WHITNEY COMPANY, on NEW YORK, N. Y., A CORPORATION or NEW JERSEY.

I- LOST-MOTION-COMPENSATING MEANS FOR GEAR-HOBBING MACHINES.

Application filed October 12,- 1922. Serial No. 594,150.

motion in the gear tram between the hob' and work spindle is eliminated.

It is an object of the invention to provide simple and inexpensive mechanism which will eliminate all inaccuracies 1n the hobbing operation due to lost motion or back lash between parts of the machine and which will not place a drag on the work spindle.

One feature which enables me to accomplish the above named object is that I provide two driving connections from the hob spindleto the work supporting and rotating spindle, one of these connectlons being a POSltlVE gear connection throughout and the other connection being a frictional one preferably comprising a train of gears provided with a frictional clutch mterposed therein. This frictional driving connection is adaptedto be driven as by a differential gear at a slightly increased speed. By this means the timing of the work spmdle is controlled entirel by the positive geared connections and t e frictionally driven connections tend to force the work ;sp1ndle as far in advance as possible, thus holding allof the lost motion or back lash, of the parts in the ositive driving connections on the 4 same si e of the gear-teeth.

Particularly, it is an object of the present invention to provide substitute means .for gthe form of lost motion compensatm means described and claimed in my copen ing application Serial No. 593,309 filed October 9,

With this and other objects in view, my

invention consists in the features of operation set forth in the followingspecification and illustrated. in I the accompanying drawing. v

In t e accompanying drawing annexed hereto and forming a part of this specification, I show in diagrammatic form a view of the cooperative mechanism of a bobbing -with the work spindle.

machine which is provided with the present invention. It will be understood, however, that the invention can be otherwise embodied and that the drawing is not to be construed as defining or limiting the scope. of the invention, the claims appended to this specification being relied upon for that purpose.

In the drawing: t

Figure 1 is a dia 'rammatic view in plan v of the mechanism orming the present invent-ion, and

Fig. 2 is a front elevation of themechanism also shown diagrammatically.

In the above mentioned drawing, I have shown but one modification of the lnvention which is now deemed preferable but it is to be understood that changes and modifications may be made within the scope of the appended claims without departing from the spirit of the invention,

Briefly, my invention in its broadest aspect comprises the following principal parts:

first, a hob supporting and rotating spindle preferably provided with suitable driving 8 means directly attached in alignment therewith; second, a work spindle adapted to rotatethe work in timed relation to the rotation of the hob spindle and adapted simultaneously to advance the work axially past the hob; third, a positive driving connection between the hob spindle and the work supportin and rotating spindle composed throug out of toothed gearing; fourth, another set of gearing including a differential gear to increase the speed ratio of this second geared connection; fifth, a friction clutch incor orated in the second drivin' connection slxt elongated pinions formmg the final elements of both of the driving connections and adapted to directly engage the indexing gear fastened directly to and moving axially Referring more in detail to the figures of the drawing, at 10 is shown a hob spindle having a hob 11 of suitable "form thereon. This hob spindle 10 is adapted to be rotated in bearings provided in the base or 1 other part of the machine shown dia rammatically at 12. Disposed at right angl es to the axis of the hob spindle is a'work spindle 14 which also may be suitably supported in the base or other part of the machine so that it may be rotated and simultaneously advanced axially. In the preferred embodi- 'ment of the invention the axes of both the hob and work spindle are fixed in predeitermined angular relation. On this spindle 14 I provide an indexing gear 15. Direct-- 1y attached to the spindle 14 by any suitable fastening means, I mount gear'blanks W which are adapted to be cut by the hob, these being mounted coaxially with the spindle in the usual way. In alignment with the work spindle 14 is a screw. 16 engaging a threaded member 17 attached to or forming a part of the base of the machine. It will be seen from this construction that as the work spindle 14 is rotated, it will be'simultaneously' advanced in an axial direction by the engagement of the screw 16 within nut 17.

In order to rotate the work spindle 14 in timed relation to the rotation of'the hob spindle 10, I provide a positive geared driving connection between these two spindles. Preferably, a bevel gear 20 fast to the hob spindle is in mesh with another bevel gear 21 on a short intermediate shaft hav mg a pinion or car 22. In mesh with the gear 22 is an i er gear 23 which in turn engages another a gear 24. Preferably the gears22 and 24 are arranged so that they may be conveniently removed and the idler so adjustably positioned that it may engage both of them. The gear 24 is fixed to and drives a shaft 25 having an elongated pinion 26. This pinion 26 is adapted to engage directly with the teeth of the indexing gear 15 inall axial positions of the work spindle 14 and gear 1 A second driving connection is provided between thehob spindle 10 and work spindle 14 which ma also be driven by the bevel gear 20 on the hob spindle 10. This drivmg connection comprises a bevel gear 30 on a shaft having a gear 31 thereon which is in mesh with an intermediate ear 32. The ear 32 is in mesh with one of t e gears 33 o a pair of ears 33 and 34, these two gears being of s ightly diflerent diameter and fastened together so that they are positively rotated simultaneously. In mesh with the gear 34 of this air is gear 35 on a shaft 36 to which is splined or otherwise fastened one set of disk members of the friction clutch 37. The other set of members and also the housing of this friction clutch 37 are fastened to or integral with an elongated pinion 38 loosely surrounding the shaft 36. Springs 39 housed within a closing member 40 of the friction clutch 37 provide means for regulating the friction within the clutch. The elongated pinion 38 driven by the clutch 37 is directly in mesh with the teeth of gear 15 throughout the axial movement of the spindle 14 and gear 15.

It will be'seen from the above construction that the timed relation between the rotation of the hob spindle 10-and the work spindle 14 is governed entirely by the posipositive] -means for said hob and s tween the gears 30 to 35 by reason of the interposition of the differential 1' 34-35 rotates the shaft 36 at' a slig tly higher speed than the shaft 25 so that the tendency of this shaft 36 through the friction clutch 37 and the pinion 38 attachedthereto is to drive the gear 15 at a slightly faster rate than called for by the positively driven pinion26. The positive connections however prevent this and cause the friction clutch 37 to slip slightly. The gear 15 however is held as far advanced as permitted by the driven pinion 26 by reason of the increase Speed of the shaft 36. Thus all lost motion or back lash between the members of the positive driving train including gears 21 to 26 is continuously held upon the same side of the teeth and any lost motion between these membersdoes not in any way affect the precision of the mechanism.-

What I claim is:

1. A gear hobbing machine having coopcrating mechanism comprising, arwork supporting and rotating spindle, a rotatable hob supporting means, a hob thereon, driving indle, two driving connections between sai hob and-spindle, and means to axially advance the work spindle during 0 erat1on..

2. A gear hob ing machine having cooperating mechanism comprising, a work sup-, porting and rotating spindle, a rotatable hob supporting means, a hob thereon, driving means for said hob and spindle, two driving connections between'said hob and spindle, elongated pinions on said driving connections, and a gear on said work spindle adapted to mesh with said pinions during operation of the. machine.

3. A gear hobbing machine having cooperating mechanism comprising, a work supporting and rotating spindle, a rotatable hob supporting means, a hob thereon, driving means for said hob and spindle, and positive and frictional driving connections between said hob and spindle.

4. A gear hobbing machine having cooperating mechanism comprising, a work supporting and rotating spindle, a rotatable hob supporting means, a hob thereon, driving means for said hob and spindle, positive and frictional driving connections between; said hob and spindle, and means to axially advancethe Work spindle during operation.

5. A gear hobbing machine having cooperating mechanism comprising, a work supporting and rotating spindle, a rotatable hob supporting means, a hob thereon, driving means for said hob and spindle, positive and frictional driving connections between said 25 v atin connections between sai hob andspindle, elon ated pinions on said positive and frictiona drivln connections,

and a gear on said work spin 1e adapted to mesh with said pinions during operation of the machine. v

6., A gear bobbing machine having coopcrating mechanism comprising, a work supporting and rotating spindle, a rotatable hob supporting means, a. hob thereon, driving means for said hob and s indie, two driving 7 hob and spindle, the ratio of said driving connectionsbeing slightly different, and a friction clutch includediin one of said driving connections.

7 A gear bobbing machine .having' cooperating mechanism comprising, a work supporting and rotating spindle, a rotatable hob supporting means,-,' a hob thereon, driving means for said hob "and spindle, two driving connections between said hob and spindle,

the ratio of said driving connections. being slightly difl'erent, and a friction clutch in- 'cluded in the faster running drivln'g connection. 1 Q 7 v 8. A gear bobbing machine having coopermechanism comprising, a work supporting and rotating spindle, a rotatable hob supporting means, a hob thereon, drivingmeans for saidhob and -spind le,.two driving connections between said hob and spmdle, the ratio of said driving connections being slightly different, a friction clutch included in one of said driving connections, and elongated pmlons on said driving connections,

and a gear on said work spindle adapted to mesh with said pinions during operation of the machine. I y

9. A gear hobbing machine having coopsignature.

crating mechanism comprising, a work ,sup-; porting and rotating spindle, a rotatable hob. supporting means, a hob-thereon, driving means for said hob disposed in alignmenttherewith, and two driving connections from.

said driving means'for said hob to said spindlewhereby said hob and spindle may be rotated intimed relation to each other,

11. A gear ho bing machine having coopeerating mechanism comprising, a work supporting and rotating spindle, a rotatable hob supporting means, a hob thereon, driving means" for said hob disposed "in alignment therewith, and two driving connections -from said driving means for said hob to said spindle whereby said hob and spindle may be rotated in timed-relation to each other, one of said connections being geared positively driven connection.

one of said connections being positive and i throughout and the other connection including a frictionclutch.

In testimony whereof, 1 hereto afiix my EARLE nUc iNeHAM. 

